Certain treatments involve, and in some cases require, the temporary or permanent interruption or modification of select nerve function. One example treatment is renal nerve ablation, which can be used to treat conditions related to congestive heart failure. The kidneys produce a sympathetic response to congestive heart failure, which, among other effects, increases the undesired retention of water and/or sodium. Ablating some of the nerves running to the kidneys may reduce or eliminate this sympathetic function, which may provide a corresponding reduction in the associated undesired symptoms.
Many body tissues, such as nerves, including renal nerves, brain tissue, cardiac tissue and the tissue of other body organs, are in close proximity to blood vessels and/or other body cavities. This proximity enables the tissues to be accessed percutaneously or intravascularly through walls of the blood vessels. In some instances, it may be desirable to ablate perivascular nerves using a radio frequency (RF) electrode. In other instances, the perivascular nerves may be ablated by other techniques, including procedures that apply thermal, ultrasonic, laser, microwave, and/or other related energy sources to the vessel wall.
Some treatment devices that are used in procedures involving perivascular nerves, such as renal nerves, employ indifferent electrodes or grounding pads to complete an electric circuit and thereby cause the delivery of electrical current to an RF electrode. In accordance with this technique, a physician carefully identifies an appropriate location of the patient's body, e.g., the patient's legs, on which to place the indifferent electrodes and to create a current path to the RF electrode for completing the circuit. However, using localized indifferent electrodes may result in more efficient modulation/ablation.
It may therefore be beneficial to provide apparatus and methods including, but not limited to, renal nerve modulation systems as well as methods of use and manufacture thereof, that increase and/or otherwise enhance the efficacy of the electrical energy delivered within an intended treatment zone of a patient's body. Additionally or alternatively, it may be beneficial to simplify use of such a device and/or reduce dependency on the patient's anatomy.